Concentration of phosphate



Patented May 8, 1934 UNITED STATES CONCENTRATION OF PHOSPHATE James T. Singleton, Fort Meade, Fla.

No Drawing. Application May 14, 1932, Serial No. 611,442

3 Claims.

My invention relates to concentration of ores, and particularly to the concentration of phosphate mineral to produce a concentrate rich in CaaPzos, commonly known as bone phosphate of 5 lime.

Phosphate mineral as taken from the earth is a mixture of phosphate with useless material such as sand, limestone and gravel with or without other undesirable material. The phosphate m may be in the form of pebbles, in the form of finer particles of pinhead size and in the form of still finer particles, perhaps fine enough to pass through a 100 mesh screen. Usually phosphate is present in all of these forms. .The recovery of the phosphate which is in the form of pebbles or coarser particles is comparatively simple and need not be here considered as my invention relates particularly to the recovery of what may be termed the very fine particles which with the finer sand and other finely divided undesirable material may pass through the screens which retain the larger particles. To recover the phosphate from this mixture in any considerable percentage has been heretofore a matter of difficulty and expense and because of this difiiculty and expense tailings containing very considerable percentages of phosphate are often thrown away.

It is the object of my invention to provide a method of so treating phosphate material, particularly that in which the phosphate is present in finely divided particles is to cause these fine particles to agglomerate into masses of such size as to be readily separated by a hydraulic classifier or other classifier operating by gravity.

In carrying out my invention I first treat the mixture consisting of or containing finely divided phosphate with finely divided undesired material with a soluble sulphide such as sodium sulphide, Nazs, using about three-fourths of a pound of sulphide to a ton of the mixture, for from five to ten minutes, the sulphide being, of course, in solution and the solution being thoroughly mixed with the material to be treated.

After this sulphidizing the slime should be washed off and after this is done soap and fuel oil at the rate of three fourths of a pound of soap and four pounds of fuel oil to the ton of material is mixed with it. The mixture is then ready for separation therefrom of the phosphate by gravity,

the agglomerated particles of phosphate being heavier and of greater mass than the fine particles of sand or other undesired material.

The mixture thus formed may be fed to an up current hydraulic classifier of usual construction in which water supplied under a constant pressure passes upward through the mixture supplied to it to carry oif the particles of undesired material with the overfiow leaving the phosphate to settle to the bottom.

Separation can, of course, be eifected by a Wilfiey table if desired instead of an up current hydraulic classifier or separation may be affected by underwater screening.

It is not necessary in carrying out my method to use the sulphide or the soap or the fuel oil in the proportion above stated as these may be varied to suit the character of the material to be treated. Nor is it necessary to use sulphide of particular purity. A poly-sulphide prepared by boiling sulphur in caustic soda may be prepared at relatively slight expense and will be found satisfactory for use in my method.

A sample of material containing 53.8 percent bone phosphate of lime and 35 percent sand treated by my above described method resulted in a phosphate product containing 78.3 percent B. P. L. and 6.1 percent sand. Further treatment of this product by screen with a stationary sloping, underwater screen preferably arranged at an angle of 55 degrees resulted in a product containing 80.9 per cent B. P. L. and 3.1 percent sand, the final products showing a recovery of 96 percent of the phosphate in the original mixture and elimination of practically all of the free sand grains. 1

My process will be found useful for improving ore preliminary to or subsequent to such ore dressing practices as flotation, screening, tabling, and the like, and will be found'particularly useful in recovering phosphate values from waste or tailing piles.

ltshould be understood that the agglomeration of tliephosphate particles may be elfected by the use of other reagents than those named. For example, sodium oleate, oleic acid, bone oil, various fatty acids or derivatives may be used to efiect the agglomeration instead of soap and fuel oil. It should be understood that the object is to agglomerate the phosphate particles so that they may be separated from the particles of undesirable material by classification as hereinabove described.

It should be understood that the sulphidizing process hereinabove described is economical in treating some ores, but it is not at all essential or necessary for obtaining the agglomeration that is secured under my process. In treating some ores it will be found more economical to use the agglomerating reagents without first using the sulphidizing agents and in all cases the sulphidizing agents can be eliminated, if desired.

Having thus described my invention what I claim is:

1. The herein described method of recovering phosphate from a mixture containing finely disists in treating the mixture with agglomera'ting 7 agents and thereby forming granules of greater mass than that of the individual sand grains and subjecting the mixture so treated to up current hydraulic classification to sink the phosphate agglomerates.

3. The herein described method of recoverin phosphate from a mixture containing sand and finely divided particles of phosphate which consists in first treating the mixture with a soluble sulphide treating the sulphidized mixture with reagents adapted to cause the particles of phosphate to agglomerate and causing them to so agglomerate into granules each of greater mass than th at of the individual sand grains and subje'cting the mixture so treated to hydraulic classification.

JAMES T. SDIGLETON. 

